河流功率梯度在泥石流空间易发程度调查中的应用:以金沙江流域为例  

Applying stream power gradient in the investigation on spatial susceptibility of debris flow: A case of the Jinsha River Basin, China

作　　者：顾畛逵 姚鑫[1,2,3] 李凌婧 陶涛 GU Zhenkui;YAO Xin;LI Lingjing;TAO Tao(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;Key Laboratory of Active Tectonics and Geological Safety,Ministry of Natural Resources,Beijing 100081,China;Research Center of Neotectonism and Crustal Stability,China Geological Survey,Beijing 100083,China;Faculty ofEngineering,China University of Geosciences(Wuhan),Wuhan 430074,Hubei,China)

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]自然资源部活动构造与地质安全重点实验室,北京100081 [3]中国地质调查局新构造与地壳稳定性研究中心,北京100083 [4]中国地质大学(武汉),工程学院,湖北武汉430074

出　　处：《地质力学学报》2023年第1期87-98,共12页Journal of Geomechanics

基　　金：国家自然科学基金项目(42107218);中国地质调查局地质调查项目(DD20221738-2);中国长江三峡集团有限公司项目(YMJ(XLD)(19)110)。

摘　　要：泥石流空间易发程度调查是开展地质灾害防范和制定生态修复计划的基础之一。目前单纯依靠野外调查并结合遥感观测,或以小流域为单元的泥石流模拟,均难以在大空间范围内高效、准确地识别潜在泥石流沟。鉴于泥石流是一种高能重力流,此次研究以金沙江流域为例,在假定物源供给无差异条件下,提出通过求算河流功率梯度(ω)来实现地表外动力活动强度定量刻画和泥石流空间易发程度调查的新方案,并将泥石流沟验证点数与ω值关系曲线的比降趋势突变位置作为阈值(1×10^(-4) W/m^(2)),提取出大约3.2万条长度超过200 m的高能河谷或泥石流易发沟谷。这些沟谷基本位于金沙江和雅砻江干流中下游,在大约30 km距离的缓冲区范围内密集分布,其数量与缓冲区宽度存在乘幂函数关系。在全球变暖背景下,未来发生极端气象事件可能性趋于增加,这些地带,尤其是梯级库区河段应做为泥石流灾害的重点防范区。研究的最终结果提供了金沙江流域泥石流易发沟谷的空间位置及ω值的点阵数据集,可供检索高能河谷的准确位置,也可作为相关地质灾害与地表过程研究的基础数据和资料。Investigation of spatial susceptibility of debris flow is a basis for carrying out geological hazard prevention and developing ecological restoration plans. It is difficult to efficiently and accurately identify potential debris flow gullies on a large spatial scale simply by relying on field surveys combined with remote sensing observations or debris flow simulations with small watersheds as units. Taking the Jinsha River Basin of China as an example, we propose a quantitative scheme to describe the intensity of extrinsic forces by calculating the stream power gradient(ω). We extracted gullies prone to debris flow, assuming that there is no spatial heterogeneity in the provenance supply conditions based on the fundamental understanding that debris flow is a high-energy gravity flow. In the situation where the threshold(ω=1×10^(-4) W/m^(2)) is the mutational site of the gradient change trend of the relation curve between the number of debris flow gullies and ω value, a total of about 32 thousand debris flow gullies with lengths of more than 200 m were found. In the middle and lower reaches of the basin, these gullies are located within a 30-kilometer buffer zone along the Jinsha and Yalong Rivers, and there is a power function relationship between the number of debris flow gullies and the width of a buffer zone. However, extreme weather events are likely to increase in the future under global warming, and these areas should be the critical prevention areas of debris flow disasters, especially the cascade reservoir area. The results of this study provide a lattice data set of spatial locations of the gullies prone to debris flow and the stream power gradients in the Jinsha River basin, which can be used to retrieve the exact location of the high-energy gullies and can also be used as the basic data for the study of related geological hazards and surface processes in general.

关 键 词：泥石流 河流功率 外动力 高能河谷 金沙江 地质灾害 

分 类 号：P694[天文地球—地质学] P642.23